Analog to digital converter with modulated feedback.

摘要

The analogue-digital converter receives an analogue input signal (x(t)) to produce a digital offset signal (y(t)). It comprises a subtracter (1) for forming the difference between the input signal and a reference signal (Ur(t)), a series of conversions (2, 3, 4) for producing the offset signal from this difference, and a feedback loop for producing the reference signal by means of a digital-analogue converter (5) which delivers a comparison signal (Uc(t)) in response to the offset signal. According to the invention, with the input signal (x(t)) having a central frequency (f0), the feedback loop comprises a shifter stage (7) for shifting the frequency response of the digital-analogue converter (5) from the zero frequency towards the central frequency (f0), this shifter stage producing the reference signal (Ur(t)) from the comparison signal (Uc(t)). <IMAGE>